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Move simple_search_memory to gdbsupport/search.cc

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This moves the simple_search_memory function to a new file,
gdbsupport/search.cc.  The API is slightly changed to make it more
general.  This generality is useful for wiring it to gdbserver, and
also for unit testing.

gdb/ChangeLog
2020-10-07  Tom Tromey  <tromey@adacore.com>

	* target.h (simple_search_memory): Don't declare.
	* target.c (simple_search_memory): Move to gdbsupport.
	(default_search_memory): Update.
	* remote.c (remote_target::search_memory): Update.

gdbsupport/ChangeLog
2020-10-07  Tom Tromey  <tromey@adacore.com>

	* Makefile.in: Rebuild.
	* Makefile.am (libgdbsupport_a_SOURCES): Add search.cc.
	* search.h: New file.
	* search.cc: New file.
This commit is contained in:
Tom Tromey
2020-10-07 12:07:55 -06:00
parent e86efb3310
commit 4a72de7366
9 changed files with 197 additions and 113 deletions
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110
gdb/target.c
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@@ -47,6 +47,7 @@
#include "event-top.h"
#include <algorithm>
#include "gdbsupport/byte-vector.h"
#include "gdbsupport/search.h"
#include "terminal.h"
#include <unordered_map>
#include "target-connection.h"
@@ -2147,106 +2148,6 @@ target_read_description (struct target_ops *target)
return target->read_description ();
}
/* This implements a basic search of memory, reading target memory and
performing the search here (as opposed to performing the search in on the
target side with, for example, gdbserver). */
int
simple_search_memory (struct target_ops *ops,
CORE_ADDR start_addr, ULONGEST search_space_len,
const gdb_byte *pattern, ULONGEST pattern_len,
CORE_ADDR *found_addrp)
{
/* NOTE: also defined in find.c testcase. */
#define SEARCH_CHUNK_SIZE 16000
const unsigned chunk_size = SEARCH_CHUNK_SIZE;
/* Buffer to hold memory contents for searching. */
unsigned search_buf_size;
search_buf_size = chunk_size + pattern_len - 1;
/* No point in trying to allocate a buffer larger than the search space. */
if (search_space_len < search_buf_size)
search_buf_size = search_space_len;
gdb::byte_vector search_buf (search_buf_size);
/* Prime the search buffer. */
if (target_read (ops, TARGET_OBJECT_MEMORY, NULL,
search_buf.data (), start_addr, search_buf_size)
!= search_buf_size)
{
warning (_("Unable to access %s bytes of target "
"memory at %s, halting search."),
pulongest (search_buf_size), hex_string (start_addr));
return -1;
}
/* Perform the search.
The loop is kept simple by allocating [N + pattern-length - 1] bytes.
When we've scanned N bytes we copy the trailing bytes to the start and
read in another N bytes. */
while (search_space_len >= pattern_len)
{
gdb_byte *found_ptr;
unsigned nr_search_bytes
= std::min (search_space_len, (ULONGEST) search_buf_size);
found_ptr = (gdb_byte *) memmem (search_buf.data (), nr_search_bytes,
pattern, pattern_len);
if (found_ptr != NULL)
{
CORE_ADDR found_addr = start_addr + (found_ptr - search_buf.data ());
*found_addrp = found_addr;
return 1;
}
/* Not found in this chunk, skip to next chunk. */
/* Don't let search_space_len wrap here, it's unsigned. */
if (search_space_len >= chunk_size)
search_space_len -= chunk_size;
else
search_space_len = 0;
if (search_space_len >= pattern_len)
{
unsigned keep_len = search_buf_size - chunk_size;
CORE_ADDR read_addr = start_addr + chunk_size + keep_len;
int nr_to_read;
/* Copy the trailing part of the previous iteration to the front
of the buffer for the next iteration. */
gdb_assert (keep_len == pattern_len - 1);
memcpy (&search_buf[0], &search_buf[chunk_size], keep_len);
nr_to_read = std::min (search_space_len - keep_len,
(ULONGEST) chunk_size);
if (target_read (ops, TARGET_OBJECT_MEMORY, NULL,
&search_buf[keep_len], read_addr,
nr_to_read) != nr_to_read)
{
warning (_("Unable to access %s bytes of target "
"memory at %s, halting search."),
plongest (nr_to_read),
hex_string (read_addr));
return -1;
}
start_addr += chunk_size;
}
}
/* Not found. */
return 0;
}
/* Default implementation of memory-searching. */
@@ -2256,9 +2157,14 @@ default_search_memory (struct target_ops *self,
const gdb_byte *pattern, ULONGEST pattern_len,
CORE_ADDR *found_addrp)
{
auto read_memory = [=] (CORE_ADDR addr, gdb_byte *result, size_t len)
{
return target_read (current_top_target (), TARGET_OBJECT_MEMORY, NULL,
result, addr, len) == len;
};
/* Start over from the top of the target stack. */
return simple_search_memory (current_top_target (),
start_addr, search_space_len,
return simple_search_memory (read_memory, start_addr, search_space_len,
pattern, pattern_len, found_addrp);
}